beat the pants off someone

beat the pants off (of) (someone)

slang To defeat someone decisively in a competition. Despite using the word "pants," this phrase does not involve literally stripping off someone's clothes. The final score was 17-1? Wow, we really beat the pants off that team!
See also: beat, off, pant
Farlex Dictionary of Idioms.

beat the pants off someone

or

beat someone's pants off

INFORMAL
If you beat the pants off someone or if you beat their pants off, you defeat them completely in a contest or competition. He brought out a chess board. `Now, Smith, I'm going to beat your pants off'. The non-academic children usually beat the pants off the rest at sport and technical work.
See also: beat, off, pant, someone
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • beat the pants off
  • beat the pants off (of) (someone)
  • beat the socks off (of) (someone)
  • beat (one's) pants off
  • lick the pants off (someone)
  • cut off at the pass, to
  • get someone's dander up, to
  • make mincemeat of
  • make mincemeat of somebody/something
  • make mincemeat of someone